This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Ran GTPase is a key regulator of many cellular processes including the transport between nucleus and cytoplasm and of the mitotic spindle assembly. Many of such functions of Ran are mediated by RanGTP induced release of importin beta-binding protein cargos. We developed strategy to isolate Ran-regulated importin beta cargos quantitatively and in a highly purified form. The identification of the importin beta "transportome" by MuDPIT analysis will facilitate the discovery and understanding of the interphase and mitotic functions of Ran.